I have only heard it once, and it was indeed radio techs. Probably wise of the dispatchers
to patch a BOLO to radio techs because they are additional eyes on the road, with instant communications back, in case they see something. Along those lines, that's another reason for all police communications to issue BOLO information on a clear channel. A homemaker washing
the dishes at the kitchen window sees the bank robber getting into a waiting car across from
her yard. Since she has just listened to her scanner, she knows to call in.
Some agencies are stupid, some are smart. The smart ones enlist all groups and
all citizens to help by broadcasting BOLO information unencrypted to all groups possible.